Support appliances

ABSTRACT

In a bed for example for hospital use in which the mattress comprises a plurality of separate air cells at different pressures, means for mounting the air cells so as to render them easily removable but at the same time with an effective air seal between the air cell and the bed even when the air cells are flexed in use.

titted States Patent [191 [[1 3,909,858

Bucket Oct. 7, 1975 [54] SUPPORT APPLIANCES 558,605 4/1896 Gimbel 51348R 4 2 H d l [75] Inventor: lFrank Edward Mayhew Ducker, 3 5 2? g iiLondon, England 3,303,518 2/1967 Ingram [73] Assignee: Watkins & WatsonLtd., London, 3,399,407 9/1968 Olsen 5/348 R England PrimaryExaminerRobert L. Wolfe [22] Flled' July 1973 Assistant ExaminerAndrewM. Calvert [21] Appl. No.: 381,646 Attorney, Agent, or FirmMarkva &Smith [30] Foreign Application Priority Data ABSTRACT July 21, 1972United Kingdom 34197/72 In a bed for example for hospital use in whichthe mat- [52] US. Cl. 5/348 1R; 128/33 tress comprises a plurality ofseparate air cells at dif- [51] Int. Cl. A47C 27/08; A61I-I 1/00 ferentpressures, means for mounting the air cells so as [58] Field of Search5/348 R, 349, 350; 128/33 to render them easily removable but at thesame time with an effective air seal between the air cell and the [56]References Cited bed even when the air cells are flexed in use.

UNITED STATES PATENTS 10 Cl 5 D F 277,979 5/1883 Blochman et al 5/350rawmg gums US. Patent 0m. 7,1975 Sheet 1 of 4 3,909,858

US. Patent Oct. 7,1975 Sheet 3 of4 3,909,858

iz-d S. Patent Oct. 7,1975 Sheet4 0f4 3,909,858

Fig.5.

SUPPORT APPLIANCES BACKGROUND OF THE INVENTION This invention relates tosupport appliances such as a bed, mattress or chair which incorporates aplurality of inflatable cells.

Experience with inflatable mattresses, particularly in hospitals, hasshown that mattresses which are composed of a number of individual aircells have pronounced advantages over mattresses of more conventionalconstruction and interest has arisen in recent years in the developmentof matresses of this type.

As described in British Patent Specifications 949,652 and 1,273,342, theprovision of a plurality of cells which can be individually inflated todifferential pressures increases the comfort and well being of hospitalpatients and other people who are obliged to lie on beds, chairs orother support appliances for long periods of time.

In using inflatable mattresses of the kind described in the above twoPatent Specifications it is necessary from time to time to removeindividual cells for cleaning or replacement. As the individual cellshave flexible walls and are contiguously arranged in these priorconstructions removal of an individual cell is virtually impossibllewithout deflating the cell and its immediate neighbours. This can be aserious disadvantage in practice since it means that the patient has tobe transferred to another bed while the necessary adjustments andreplacement are made.

Furthermore, in using cells in beds of which various sections can betilted to support the patient, for example, in an upright sittingposition compression fittings and other types of connection between theair cells and the frame of the bed have in the past been found to beunsuitable as the air connection very often pulls out from the frame andthe cells deflate. This has been a considerable problem in practice.

The present invention is concerned with methods of locating andanchoring a plurality of cells in an inflatable mattress whichfacilitates replacement of individual cells as desired and whichprovides an air tight seal even when the inflatable cells flex relativeto the base of the support appliance SUMMARY OF THE INVENTION Accordingto one aspect of the present invention there is provided a supportappliance which comprises a plurality of inflatable cells mounted on abar arranged parallel to the length of the cells, inlet and/or outletmeans for air being provided between the bar member and each associatedair cell.

In this way, the air cell is able to pivot about the bar as the patientmoves or as the various sections of the bed are hinged relative to oneanother. As the air cell pivots about the bar and the air connection forthe air cell is provided in the bar, there is less likelyhood of airleaks caused by pivoting and movement of the air cell since the degreeof relative movement is greatly reduced.

In a preferred arrangement the bar is provided in the form of a tubularmember.

Preferably a layer of resilient material is provided on the top surfaceof each bar or tubular member, and the air inlet and/or outlet in thebar or tubular member comprises an aperture through the resilientmaterial and the top surface of the bar or tubular member. The

resilient material may comprise a layer of foam rubber about 1 inchthick. The inlet and/or outlet for the air cell then preferablycomprises a rigid nozzle member which tightly engages the aperturethrough the resilient material to provide a seal. Preferably the bar ortubular member has two inlet and/or outlets adjacent opposite ends, onebeing for air supply to the air cell and one for exhaust of air from theair cell. If the bar is a tubular member then this will necessitate aninternal stop between the two apertures in the tubular member.

If the support appliance is in the form of a bed, then preferably thebar or tubular member extends transverse to the length of the bed andrests on frame members along each side of the bed. The frame members arepreferably hollow and cooperating apertures are provided in the framemembers and the bar and air may be passed from one frame member througheach bar to the interior of an associated air cell and out from theinterior of the associated air cell through the other aperture in thebar to the other frame member.

According to a further aspect of the invention the inflatable cells areconnected to inlet and/or outlet means for air by forming holes in thebase of the individual cells which are located over corresponding holesin the base of the support appliance, the support appliance in the areasof the holes providing a firm surface so that pressure of air in thecells effectively seals the base of the individual cells around theinlet and/or outlet means.

According to an additional] aspect of the invention, there is providedan inflatable cell primarily, for use in a support appliance of the typedescribed and having internal means for restraining expansion under theinfluence of pressure of a gas introduced therein. The means forrestraining expansion conveniently takes the form of strips, ribbons,webs or the like which are connected at their ends to opposed walls ofthe cell and which have a dimension which prevents expansion of thecells by more than a predetermined amount under internal air pressure.The strips, ribbons, or webs may be of the same or different material asthe cells and may be attached to the walls of the cells by welding,stitching riveting bonding or other convenient means. It will beappreciated that by restraining expansion of the cells in this way in adesired direction, removal of an individual cell is facilitated sinceadjacent cells will not exert significant lateral force on a cell to beremoved.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation from one side of onesection of a bed in accordance with the invention;

FIG. 2 is a section taken along line AA in FIG. 1;

FIG. 3 is an elevation from one side of a modified bed section inaccordance with the invention;

FIG. 4 is a section taken along the line BB in FIG. 3, and,

FIG. 5 is a section similar to FIG. 4 of an alternative embodiment ofthe invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, theFigures show a section of a bed including a base portion 1 andinflatable cells 2 (of which only the lower portions are shown) forminga mattress section. A number of bed sections, e.g. 3 or 4, are coupledtogether with articulated connections to form a complete bed asdescribed in our copending British Patent application no. 11942/73 or inthe Lancet Oct. 23rd, 1971 pages 885 to 888. The base portion comprisesa pair of tubular frame members 3 which form both the frame of the bedand also serve as the supply and exhaust conduits for the air for theinflatable cells. Supported on the frame members 3 are a series of crossmembers or bars 4 (one for each cell) which are constructed from wood,steel or other substantially rigid material and which are bolted to theframe members 3 by bolts 5 or loosely located by locating ears on theframe member 3. Pairs of blocks 6, of substantially rigid material (onepair for each cell) are mounted opposite each other on each side of thebed and at spaced intervals along its length. Holes 7 and 8 respectivelyare formed in each block 6 and are aligned with corresponding holes 9and 10 in the bar 4 and in the upper wall of tubular members 3. Theseholes provide for supply of air at low pressure e.g. up to about 5-15inches water gauge, to the cells and removal of air therefrom. The airmay be heated.

Cross member 4 is formed with slots 11 and 12 on each side of blocks 6and these slots extend across the width of the bed section. Slots 11 and12 communicate with tubular cavities 13 and 14 formed partly by ahollowed out portion of the bar 4 and partly by a plate 15. Aninflatable cell 2 (which is approximately sausage shaped) extends acrossthe width of the bed section and is in contact at its ends with blocks6. Each cell 2 is anchored to the bed section 1 by an anchoringarrangement including a pair of ropes l6 and 17 which are receivedrespectively in tubular cavities 13 and 14. Attached to ropes l6 and 17is a web of material 18 which is in the form of a loop, the ends of theweb being connected to the ropes 16 and 17 while the middle portion isattached to or forms the base of cell 2. Each inflatable cell 2 isformed with holes 19 and 20 which are aligned with holes 7 and 8 in theblocks 6.

Excess material is provided in the base portion of the inflatable cell 2in the regions of the holes 19 and 20 so that on inflation of the cell,pressure of air in the cell presses the base of the cell, in thevicinity of holes 19 and 20, firmly into contact with the blocks 6 andthereby forms an air tight seal. Individual cells can be removed fromthe bed section by slightly deflating the appropriate cell and drawingthe cell outwardly i.e., from the plane of the paper in FIG. 2. In orderto locate the cell widthwise of the bed, downwardly extending webportions 21 and 22 are provided which may be secured by Velcro orsimilar quick release system to a part of the bed section 1, e.g. to theframe members 3.

Conveniently the spaces between blocks 6 are filled with a rubber orplastic foam material 23.

In order to limit lateral expansion of the cells 2, a membrane similarto membrane 24 in FIGS. 4 and 5 divides each cell longitudinally and isattached by any suitable means to the cell walls. The membrane is apertured to allow air to circulate through the entire interior of thecells. The dimensions of the membrane are chosen so that undue lateralforce is not exerted by the cells on neighbouring cells.

It will be appreciated that in the arrangement illustrated in FIGS. 1and 2, the pressure and through flow of air will normally be identicalin each cell. In some circumstances it may be desirable to vary the flowof air through one individual cell and this can be achieved by fitting abush 25 in hole 19 having a greater or smaller orifice than those in theother cells in the bed section depending on whether a larger or smallerthrough flow is desired.

Removal of a cell in the arrangement illustrated in FIGS. 1 and 2 isexceedingly simple. A blanking plate may be slidably mounted on the topsurface of each block 6 so that it can be moved from an inoperativeposition to an operative position where it blanks off the inlet hole 8and depressurises its associated cell without interfering with the airsupply to the remaining cells in the section. Web portions 21 and 22 arefreed from their fastenings and the selected cell can then be drawn out.Replacement of a cell is achieved by the reverse of these operations.

Referring to FIGS. 3 and 4, the construction shown therein represents amodified arrangement for mounting and anchoring the cells to the bedsection. The frame of the bed section is formed from a pair oflongitudinally extending tubular frame members 33 upon which are mounteda plurality of cross members 34 which are spaced apart lengthwise of thebed section. Interposed between each pair of adjacent cross members istubular secondary member 35 having closed ends and a blocked off centralportion to prevent air flowing therethrough. Secondary members 35 areclamped at each end to tubular members 33 so that holes in members 33align with corresponding holes in members 35 in an air-tight manner bymeans of a seal 41. Air is supplied to each cell 36 from its associatedmember 35 via a nipple 37 screwed into member 35. Each cell 36 is formedwith a hole into which nipple 37 is received and the materialsurrounding the hole is reinforced with a rubber annulus 38. Sealing ofthe cells onto the member 35 is achieved by the pressure of air in thecells. Rimilar provision is made at the other end of the cell for lfowof air from the cell. Each cell 36 is anchored to the member 35 by webs39 and 40 extending lengthwise of the cell which are secured to eachother by press studs, Velcro or similar material. The tops of the crossmembers 34 are padded with plastics or rubber foamed strips 42.

An important advantage of the construction described in the figures isthat the cells show little tendency to leak at their points ofconnection to the air inlet and return conduits even when the cells aredeflected by articulation of the individual bed sections to contour theupper surface of the mattress as shown in the Figures of the Lancetarticle referred to above.

It may not be essential in all instances to provide an outlet 19 forescape of air from the cells 2 where the cells are provided with poressince the flow of air may be controlled through such pores.

Lateral expansion of the cells is preferably controlled by membranes 24as shown in FIGS. 4 and 5 since this enables the shape of the cells tobe retained more easily in their expanded condition independently ofadjacent cells. It will be appreciated that there may be more than onemembrane in each cell and the membranes are not necessarily parallel tothe top surface of the bed section. For example the membranes may dividethe interior of each cell into a number of honeycomb compartments or mayinduce the air to flow in a tortuous path through the cell. Air in thecell may be induced in this way to flow generally parallel to the uppersurfaces of the cell and this may facilitate control of the temperatureof the user of the bed or, by provision ofporous cell fabric, extractionof water vapour or other gases released by wounds or injuries.

The embodiment shown in FIG. 5 is generally similar to FIG. 4. However,it has been founda bed can be produced without the cross members 34 orstrips 42, if the tubular members 35 are increased in size. In theembodiment of FIG. 5 the tubular members 35 have been enlarged and areconstructed of steel tubes coated with a plastic material. It will beseen that each tublar member 35 includes a layer on its top surface of 1inch thick sponge rubber 50. The air cells 36 each include twoapertures, one adjacent each end with rigid nozzles 51, the rigidnozzles 51 including a collar 52 around their inner end for easyattachment of the nozzles 51 to the air cells. The air inlet and/oroutlet in the member 35 is provided by an aperture 53 through the spongerubber layer 50 and through the top surface 54 of the tubular member 35.The diameter of the aperture through the sponge rubber, layer 50 isnarrower than the outer .diameter of the nozzleSl so that an air seal isprovided. However, as with the previous embodiments, as a safeguardthere is provided a loose layer of material around the nozzle 51 in eachair cell and betwen the webs 39 and 40 which under the influence of theair pressure within the air cell will provide a seal around eachaperture.

It has been found preferable to delete the presence of members 34, 42since this simplifies the cleaning of the bed, a matter of paramountimportance in the use of such beds in hospitals.

Furthermore, by the use of simple plug connections between the air celland the members 35 the removal and insertion of the air cells is greatlyfacilitated. Further, the members 35 support the air cells and eachmember 35 provides a pivot about which the associated air cells may to alimited extent rotate as the patient moves on the bed or if the bed isprovided in sections which hinge relative to one another.

Various means may be provided for anchoring the webs 39, 40 to themember 35. In the arrangement shown in FIG. 5 there is provided alongeach side of the member 35 further bars 55, 56 which are clamped to theside faces of the member 35 by clamping means which are releasable fromeach end of the member 35. The webs 39, 40 are wrapped around the bars55, 56 and anchored thereto by frictional clamping between the bars55,56 and the side surfaces of the member 35.

I claim:

1. A support appliance which comprises a. a plurality of elongatedtubular members;

b. a plurality of elongated inflatable cells, each arranged parallel toone of said tubular members;

c. means mounting each said cell on the respective tubular member;

d. separate inlet and outlet apertures extending through the wall ofsaid cell and through the adjacent wall of the respective tubularmember; and

e. a layer of foam rubber positioned between each said cell and saidrespective tubular member, said inlet and outlet apertures extendingthrough the wall of said cell, through said foam rubber and through theadjacent wall of the respective tubular member;

f. whereby a continuous flow of pressurized air may be maintained ineach of said cells between the inlet and outlet apertures thereof.

2. A support appliance as claimed in claim I further comprising a rigidnozzle member in tight sealing engagement with each of said inlet andoutlet apertures.

3. A support appliance which comprises a. a plurality of elongatedtubular members;

b. a plurality of elongated inflatable cells, each arranged parallel toone of said tubular members and including a pair of spaced parallel webmembers attached generally along the length of the exterior of the aircell, said web members extending along opposite sides of the respectivetubular member;

0. means for anchoring said web members to the respective tubularmembers, said adjacent wall of said tubular members being between saidpair of web members; and

(1. separate inlet and outlet apertures extending through the wall ofsaid cell and through the adjacent wall of the respective tubularmember;

e. whereby a continuous flow of pressurized air may be maintained ineach of said cells between the inlet and outlet apertures thereof.

4. A support appliance as claimed in claim 3 wherein said means formounting each said cell comprises means for anchoring said web portionsto the opposite sides of each of said elongated tubular members suchthat the elongated portion of said cell between said web portions andadjacent the surface of said tubular member is maintained relativelyslack whereby the air pressure within each air cell presses said slackportion against the surface of said tubular member to provide a sealabout said inlet and outlet apertures between the surface of the tubularmember and said cell.

5. A support appliance as claimed in claim 3 wherein said mounting meanscomprises fixed members spaced on said opposite sides of said tubularmembers forming narrow elongated slots between said fixed members andsaid opposite sides of said tubular members, a hem along the free end ofeach of said web portions and rigid elongated means having a widthgreater than said slot mounted in each hem whereby each said web memberis anchored in one of said slots, movement through said slot beingprevented by said rigid elongated means in said hem.

6. A support appliance as claimed in claim 3 wherein said mounting meanscomprises a plurality of rigid elongated members mounted adjacent saidopposite sides of each of said tubular members, each said web memberpassing around one of said rigid elongated members to secure said webmember between one of said bars and the respective side of a tubularmember.

7. A support appliance which comprises a. a base having a firm surfacethereon,

b. at least one air cell mounted on said base,

c. air inlet and outlet means. extending between said air cell and saidbase, said air inlet and outlet means comprising holes in said firmsurface of said base-aligned with holes in the wall of said cell,

d. means attached to the wall of said cell at at least two positionsspaced from the holes in the wall of said cell for attaching said cellto the base such that a relatively slack portion of the cell wall isprovided about each hole,

e. whereby air pressure in said air cell causes the slack portion ofsaid cell to effectively seal with said firm surface of said base aboutsaid holes.

8. A support appliance which comprises a. a plurality of elongatedtubular members;

b. a plurality of elongated inflatable cells, each arranged parallel toone of said tubular members;

c. means mounting each said cell on the respective tubular member;

d. separate inlet and outlet apertures extending through the wall ofsaid cell and through the adjacent wall of the respective tubularmember;

e. a layer of resilient material positioned between each said cell andsaid respective tubular member, said inlet and outlet aperturesextending through the wall of said cell, through said resilient materialand through the adjacent wall of the respective tubular member; and

f. a rigid tubular nozzle member extending through and in tight sealingengagement with each of said inlet and outlet apertures;

g. whereby a continuous flow of pressurized air ma be maintained in eachof said cells between the inlet and outlet apertures thereof.

9. A support appliance in the form of a bed which comprises a. a pair ofelongated hollow frame members extending the length of the bed alongopposite sides thereof;

b. a plurality of elongated tubular members extending transversely tothe length of the bed and being supported on said frame members adjacentthe opposite ends thereof;

c. cooperating apertures extending from a wall in each of said hollowframe members to a wall in each of said tubular members;

(1. a plurality of elongated inflatable cells, each arranged parallel toone of said tubular members;

e. means mounting each said cell on the respective tubular members; and

f. separate inlet and outlet apertures extending through the wall ofsaid cell and through the adjacent wall of the respective tubularmember;

g. whereby a continuous flow of pressurized air may flow from theinterior of one of said hollow frame members through one of saidcooperating apertures to all of said tubular members, through said inletapertures to all of said cells, through said outlet apertures to all ofsaid tubular members and finally through the other of said cooperatingapertures to the other of said hollow frame members.

10. A support appliance which comprises a. a plurality of elongatedtubular members;

b. a plurality of elongated inflatable cells, each arranged parallel toone of said tubular members; c. means mounting each said cell on therespective tubular member;

d. separate inlet and outlet I apertures extending through the wall ofsaid cell and through the adjacent wall of the respective tubularmember; and

e. a layer of resilient material positioned between each said cell andsaid respective tubular member, said inlet and outlet aperturesextending through the wall of said cell, through said resilient materialand through the adjacent wall of the respective tubular member;

f. said plurality of cells being arranged in a plurality of groups, allthe cells in one group being adapted to be maintained at one airpressure while the pressure of the remaining groups are independentlycontrollable;

g. whereby a continuous flow of pressurized air may be maintained ineach of said cells between the inlet and outlet apertures thereof. l

1. A support appliance which comprises a. a plurality of elongatedtubular members; b. a plurality of elongated inflatable cells, eacharranged parallel to one of said tubular members; c. means mounting eachsaid cell on the respective tubular member; d. separate inlet and outletapertures extending through the wall of said cell and through theadjacent wall of the respective tubular member; and e. a layer of foamrubber positioned between each said cell and said respective tubularmember, said inlet and outlet apertures extending through the wall ofsaid cell, through said foam rubber and through the adjacent wall of therespective tubular member; f. whereby a continuous flow of pressurizedair may be maintained in each of said cells between the inlet and outletapertures thereof.
 2. A support appliance as claimed in claim 1 furthercomprising a rigid nozzle member in tight sealing engagement with eachof said inlet and outlet apertures.
 3. A support appliance whichcomprises a. a plurality of elongated tubular members; b. a plurality ofelongated inflatable cells, each arranged parallel to one of saidtubular members and including a pair of spaced parallel web membersattached generally along the length of the exterior of the air cell,said web members extending along opposite sides of the respectivetubular member; c. means for anchoring said web members to therespective tubular members, said adjacent wall of said tubular membersbeing between said pair of web members; and d. separate inlet and outletapertures extending through the wall of said cell and through theadjacent wall of the respective tubular member; e. whereby a continuousflow of pressurized air may be maintained in each of said cells betweenthe inlet and outlet apertures thereof.
 4. A support appliance asclaimed in claim 3 wherein said means for mounting each said cellcomprises means for anchoring said web portions to the opposite sides ofeach of said elongated tubular members such that the elongated portionof said cell between said web portions and adjacent the surface of saidtubular member is maintained relatively slack whereby the air pressurewithin each air cell presses said slack portion against the surface ofsaid tubular member to provide a seal about said inlet and outletapertures between the surface of the tubular member and said cell.
 5. Asupport appliance as claimed in claim 3 wherein said mounting meanscomprises fixed members spaced on said opposite sides of said tubularmembers forming narrow elongated slots between said fixed members andsaid opposite sides of said tubular members, a hem along the free end ofeach of said web portions and rigid elongated means having a widthgreater than said slot mounted in each hem whereby each said web memberis anchored in one of said slots, movement through said slot beingprevented by said rigid elongated meanS in said hem.
 6. A supportappliance as claimed in claim 3 wherein said mounting means comprises aplurality of rigid elongated members mounted adjacent said oppositesides of each of said tubular members, each said web member passingaround one of said rigid elongated members to secure said web memberbetween one of said bars and the respective side of a tubular member. 7.A support appliance which comprises a. a base having a firm surfacethereon, b. at least one air cell mounted on said base, c. air inlet andoutlet means extending between said air cell and said base, said airinlet and outlet means comprising holes in said firm surface of saidbase aligned with holes in the wall of said cell, d. means attached tothe wall of said cell at at least two positions spaced from the holes inthe wall of said cell for attaching said cell to the base such that arelatively slack portion of the cell wall is provided about each hole,e. whereby air pressure in said air cell causes the slack portion ofsaid cell to effectively seal with said firm surface of said base aboutsaid holes.
 8. A support appliance which comprises a. a plurality ofelongated tubular members; b. a plurality of elongated inflatable cells,each arranged parallel to one of said tubular members; c. means mountingeach said cell on the respective tubular member; d. separate inlet andoutlet apertures extending through the wall of said cell and through theadjacent wall of the respective tubular member; e. a layer of resilientmaterial positioned between each said cell and said respective tubularmember, said inlet and outlet apertures extending through the wall ofsaid cell, through said resilient material and through the adjacent wallof the respective tubular member; and f. a rigid tubular nozzle memberextending through and in tight sealing engagement with each of saidinlet and outlet apertures; g. whereby a continuous flow of pressurizedair may be maintained in each of said cells between the inlet and outletapertures thereof.
 9. A support appliance in the form of a bed whichcomprises a. a pair of elongated hollow frame members extending thelength of the bed along opposite sides thereof; b. a plurality ofelongated tubular members extending transversely to the length of thebed and being supported on said frame members adjacent the opposite endsthereof; c. cooperating apertures extending from a wall in each of saidhollow frame members to a wall in each of said tubular members; d. aplurality of elongated inflatable cells, each arranged parallel to oneof said tubular members; e. means mounting each said cell on therespective tubular members; and f. separate inlet and outlet aperturesextending through the wall of said cell and through the adjacent wall ofthe respective tubular member; g. whereby a continuous flow ofpressurized air may flow from the interior of one of said hollow framemembers through one of said cooperating apertures to all of said tubularmembers, through said inlet apertures to all of said cells, through saidoutlet apertures to all of said tubular members and finally through theother of said cooperating apertures to the other of said hollow framemembers.
 10. A support appliance which comprises a. a plurality ofelongated tubular members; b. a plurality of elongated inflatable cells,each arranged parallel to one of said tubular members; c. means mountingeach said cell on the respective tubular member; d. separate inlet andoutlet apertures extending through the wall of said cell and through theadjacent wall of the respective tubular member; and e. a layer ofresilient material positioned between each said cell and said respectivetubular member, said inlet and outlet apertures extending through thewall of said cell, through said resilient material and through theadjacent wall of the respective tubular member; f. said plurality ofcells being arranged in a plurality of groups, all the cells in onegroup being adapted to be maintained at one air pressure while thepressure of the remaining groups are independently controllable; g.whereby a continuous flow of pressurized air may be maintained in eachof said cells between the inlet and outlet apertures thereof.